1. Field of the Invention
The present invention relates to a washing machine, and more particularly to a washing machine having an impeller mounted on the bottom of a basket or tub and rotatable for washing clothes.
2. Description of the Prior Art
There are known different types of washing machines in the art. One form of washing machine produces a spiral current of water in a basket or tub for washing clothes therein, while another washing machine type agitates water in the basket in washing operation.
The former type of washing machine employs an impeller disposed on the bottom of the basket and rotatable at a high speed for generating a spiral current of water in the basket to wash clothes therein. The impeller generally comprises a disk-shaped base, a projection integrally extending from the disk-shaped base, and a plurality of ridges or vanes integrally and smoothly extending from a barrel wall of the projection radially outwardly over the disk-shaped base. The projection has a height which is about 1/5-1/6 of the outside diameter of the disk-shaped base, so that the upper end of the projection is located far below the level of water in the basket, as shown in U.S. Pat. No. 3,306,082. The impeller usually rotates at a high speed in the range of from 400 to 800 rpm. The vortex of water produced in the basket during operation of the washing machine is strong enough to rotate the wash forcibly and clean the same, but so intensive that the clothes being washed tend to be damaged.
The washing machines for agitating water in the basket comprise an agitator having a height which is about 1.5 times greater than the outside diameter of a base of the agitator, the agitator having an upper end projecting upwardly beyond the level of water in the basket while the water is kept at rest. The agitator includes a plurality of relatively large ridges or vanes integrally formed on the base. In operation, the agitator oscillates about its own axis alternately clockwise and counterclockwise in an angular interval smaller than complete revolution for agitating water and clothes. U.S. Pat. No. 3,526,105 is representative of such a washing machine. The agitator turns in each cycle at a low speed of about 100 rpm. This type of washing machine is more advantageous than the impeller-type washing machine in that the wash is subject to less damage. However, with the agitator having a higher projection, upper and lower layers of clothes being washed do not switch around frequently, and thus are cleaned irregularly, that is, cannot be cleaned sufficiently.